Studies in Human Biology. by Raymond PearlReview by: E. M. N.Journal of the Royal Statistical Society, Vol. 89, No. 1 (Jan., 1926), pp. 151-152Published by: Wiley for the Royal Statistical SocietyStable URL: http://www.jstor.org/stable/2341492 .

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1926.] Reviews of Statistical and Economic Books. 151

some method, and by assuming lags between the two rates of different times (e.g., one year, two years, three years). The cQn- clusions reached are that the smallness of the correlation found between the two rates suggests-in these two countries at these periods-that the other factors recognized by Malthus had an appreciable effect: in other words, that population pressure had very little existence, or was relieved by such factors as emigration, increase of food supply, etc. F. S.

5.-Studies in Human Bio7ogy. By Raymond Pearl. 653 pp. Baltimore: Williams and Wilkins Co. 1924. Price $8.

This book is a collection of Professor Pearl's writings over a period of more than twenty years. In his preface the author says that the only claim for unity in such a book is such as is inherent in the point of view of the author. That this point of view accepts the widest modern interpretation of the word biology as including the study of men as a community, and not only man as an individual, is evident from the range of subjects covered by the volume, which begins with a careful biometric study of brain weight, and ends with a section on population growth. One large branch of human biology, however-the mental and psychological-is barely touched.

The papers are collected under four headings :-Considering Man as an Animal, The Biological Aspects of Vital Statistics, Public Health and Epidemiology, and the Population Problem.

Of the six papers in the first section, that on the weight of the human brain is the most comprehensive, and gives a thorough and careful analysis of the available material. One minor point in it that the author has overlooked in his revision is a statistical mis- statement on pp. 78 and 80. The multiple correlation coefficient cannot, of course, ever be less than the absolute value of any of the corresponding total coefficients. The apparent paradox discussed arises simply from an arithmetical slip.

Two short papers deal with the sex ratio, one from the point of view of racial crossing, the other dealing with the generally higher ratio among the Jews, but the author has not pursued this question very far.

The most interesting paper in the section on vital statistics is the short comparative study of the mortality of man and of the Drosophila fly, and of the rotifer Proales decipiens. The life span of other animals than man is an almost untrodden field.

Professor Pearl's "Vital Index" (births: deaths) shares the disadvantage common to all such indices-that the more they include, the more they conceal. If a single index is to be used to measure " the biological essentials of a population," there is, perhaps, little to choose between the different forms that suggest themselves, but it is open to question whether the difference between the birth- and death-rate, rather than their ratio, does not give a more direct and simple measure of the natural increase of a population. The

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152 Reviews of Statistical and Economic Books. [Jan.

idea behind the vital index calculated for specific age-groups is not altogether clear.

Taken as a whole, the author's papers on vital statistics show a stimulating fertility of mind which gives freshness to his treatment, though at times one feels that depth has been sacrificed to breadth.

The last section deals with a subject of which Professor Pearl has made a special study, and his rediscovery and wide applications of Verhulst's " logistic " curve for the growth of human populations are well known. As a descriptive tool and for interpolation purposes the curve promises to be of good service, but how much one looks on this as simply the result of the chosen equation being of the required flexibility, given a reasonable number of constants and the necessary dash of " e " usually called for in curves of growth, and how much one regards the asymptotic form as representing a real underlying biological law of any prediction value is a matter of individual temperament. The example of the curve for Japan stresses the need for caution in extrapolation. A closer association of these curves with the underlying social and industrial factors which shape their course would add much to their interest.

To discuss even superficially the many subjects treated in these essays would be beyond the limits of a review, and we must content ourselves with assuring even the most non-technical reader that, in spite of their statistical nature, he will not find them dull. Pro- fessor Pearl has a flowing pen and the tendency to follow new lines of thought.

The publisher's note giving the names of all members of their staff who have helped in the manufacture of this book is a custom which has much to be said for it as an encouragement to individual responsibility and pride in good work, and is here fully justified by the result. E. M. N.

6.-The Confessions of a Capitalist. By Sir E. J. P. Benn, Bt. 287 pp. Hutchinson & Co., Ltd. Price i8s. net.

Confessions, as the late Lord Salisbury might have said, are always interesting, from St. Augustine to Rousseau, and from Rousseau to Sir Ernest Benn. But this book, though it makes capital reading, is less a confession than an apologia, in which the author states simply and forcibly the case for the capitalist manager in the business world. Politically Sir Ernest Benn is a convinced individualist, having no belief in the " State " action now so fashion- able in each of our three parties, nor does he share the prejudice against profits which grew up during the war. On the contrary, he declares that his own profits have always made profits for everyone else with whom he was dealing, and he contends, justly enough, that profits are not an addition to prices, but an incentive to greater production and lower prices; high profits, indeed, are their own cure. Sir Ernest Benn has been a business man since the age of sixteen; as his parents married young, and had a laTge fanmily, he escaped the handicap of a university education. He has the highest

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